Execution of the Circadian Negative Feedback Loop in Neurospora Requires the ATP-Dependent Chromatin-Remodeling Enzyme CLOCKSWITCH

William J. Belden, Jennifer J. Loros, Jay C. Dunlap

Research output: Contribution to journalArticlepeer-review

96 Scopus citations

Abstract

In the Neurospora circadian system, the transcription factors White Collar-1 (WC-1) and White Collar-2 (WC-2) activate expression of frq, whose gene product inhibits its own expression. The WC proteins are thought to form an obligate complex; however, chromatin immunoprecipitation (ChIP) indicates that WC-2 binds to the frq promoter in a rhythmic fashion, whereas WC-1 is bound continuously. Small oscillations in histone acetylation are detected over the circadian cycle with a marked reduction upon light-induced activation. Nuclease accessibility experiments indicate chromatin rearrangement at the frq promoter; therefore, 19 genes with homology to ATP-dependent chromatin-remodeling enzymes were deleted and the strains examined for clock phenotypes. One gene, designated clockswitch (csw-1), is required for clock function; its product localizes to the frq promoter, is required for proper frq expression, and has an impact on chromatin structure. The data suggest that CSW-1 regulates accessibility of promoter DNA, thus generating the sharp transition from the transcriptionally active to the repressed state.

Original languageEnglish (US)
Pages (from-to)587-600
Number of pages14
JournalMolecular cell
Volume25
Issue number4
DOIs
StatePublished - Feb 23 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

Keywords

  • CELLCYCLE
  • DNA

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